Improvement in the manufacture of straw paper



UNITED STATES ATENT Erica.

ROBERT T. SMART, J. 7. SMART, AND A. J. SMART, OF TROY, NEW YORK.

IMPROVEMENT IN THE MANUFAGTURE OFSTRAW PAPER.

Specification forming part of Letters Patent No. FY3853, dated March 27,1560.

To all whom it may concern:

Be it known that we, ROBERT '1. SMART, J OSEPH W. SMART, and ANDREW J.SMART, of Troy, in the county of Itensselaer and State of New York, haveinvented a certain new and useful Process for Making White Paper fromStraw or Similar Substances; and we do hereby declare that the followingis a full, clear, and exact description of the nature of said processand the effect thereof on the pulp and paper produced from straw orsimilar material.

In the manufacture of white paper from straw and similar vegetablefibers several methods have been pursued, among which may be mentionedthat set forth in Letters Patent No. 9,910, wherein hydrate of soda orpotash is used in a peculiar apparatus to operate upon straw cut up by achaff-cutter. After this operation the straw is washed in a mass andbefore the fibers are separated or opened. The mass is then subjected tohypochlorite of alumina for bleaching. The half-stuff, after all thesechemical operations have been performed on' the unseparated mass, iswashed and beat in an ordinary engine and made into paper. Anotherprocess set forth in Letters Patent No. 17,387 relates to subjectingstraw, 850., to heat, pressure, and agitation in a boiler containin galkali, then the stuff is washed, steeped in sulphuric acid, washed,bleached, and then beat into pulp; and a somewhat similar process hasbeen pursued, (see Patent No. 26,202,) using a stronger alkali andgreater pressure.

Our invention and process differ from all others in the manner and orderin which our successive operations are performed, whereby the fibers aremore thoroughly separated and perfectly bleached, so that the paperproduced in entirely free from colored spots and much stronger onaccount of the perfect separation of the fibers in the pulp-engine andby the operations to which they are subjected.

In all the processes heretofore in use with which we are acquainted thebleaching operation was performed upon the straw or similar fiber beforeit was reduced to half-stuff, or when it arrived at this stage in thepaper-making and before being reduced to pulp. The consequence was thatthe chemical bleaching agents did not penetrate and remove all thecoloring-matter from the knots and thick or lumpy parts, and hence whenbeat into pulp and formed into paper spots of coloring-matter wereclearly visible. Besides this the bleaching agent required to be verypowerful to penetrate the straw, and even then did not act upon theseparate fibers in the efficient manner necessary to make a good qualityof white paper quite free from coloring-matter.

In preparing paper-pulp we pursue the following method:

First. We take the straw, either cut or uncut, or other vegetable matterproperly reduced, if necessary, by cutting, grinding, or breaking, andplace the same in a suitable vat or tub containing a strong alkalinesolution and boil the same by steam or fire heat; and for this purposewe make use of soda-ash or potash, either alone or in connection withhydrate of lime. This operation is continued the necessary or desiredlength of time, until the silicious or aluminous matter is loosened orseparated from the vegetable fiber and the mass reduced to the properstate for the next operation.

Second. We place said vegetable fibrous matter in any ordinary orsuitable engine, in which the same is thoroughly washed and the fibersseparated or reduced to a pulp.

Third. From the pulp-engine the material is passed into a receivingchest or tub, and then we allow a small stream of pulp to run into a vatthrough which a stream of clean water is flowing. The pulp as carriedalong with the water is thoroughly washed and opportunity given for anyheavy lumps and unseparated parts to subside, and receptacles may beformed for these by pieces of board set across the bottom of said vat.The water passes through a cyl--- inder covered with wire-cloth, whichcylinder arrests and in its revolutions lifts out the pulp. The fibersare taken up and the water expressed by press-rollersu Fourth. Thefibers, being separated and reduced to a soft pulp by the foregoingoperation, are put into an engine or vat and chloride of lime applied tothe same. We afterward add sulphuric acid in such proportions andstrength as may be necessary, accordingto the character of the stockoperated on. These chemical agents act to separate and remove anyalbuminous, silicious, or woody matter from the fibers and commence thebleaching operation, and in the fine state to which the stock has beenreduced these agents act much more thoroughly and effectively. At thesame time they do not require to be of so great strength as necessaryfor operating upon the half-stuff, as heretofore practiced.

Fifth. After submitting the pulp to the foregoing operation for thenecessary length of time-say from six to twenty-four hours, according tocircumstances-the pulp is to be thoroughly washed and cleaned in eitherengine or vat, and chloride of lime applied in sufficient quantity andallowed to remain the necessary time to bleach the fibers to the desiredwhiteness, and. then the pulp is made into paper in the usual manner;and for this purpose the pulp may be either washed again or put into apulp-engine for beating the fibers still finer, if a better quality ofpaper is to be made.

Upon examination of paper produced by our process and comparing the samewith any paper made by others from a corresponding stock it will befound that our article is free from yellow or colored spots, while thatheretofore made from straw contains more or less spots of a yellowishcolor when viewed by transmitted light, said spots arising from the factthat the bleaching agents are applied before the paper is reduced topulp, so that such chemical agents do not act uniformly and thoroughlythroughout the particles; and besides this byour process all foreignsubstances are so effectually removed from the fibers that there isnothing to impede or neutralize the bleaching chemicals.

The paper made by our process is not only whiter and clearer from yellowspots caused by particles remaining in their natural color and proving ablemish and imperfection in the manufacture, but it is also very muchstronger and tougher than paper ever before made from straw or similarvegetable fibrous substances. In fact, it is strongeraud tougher thanmostof the paper made from rags.

I We do not claim the use of alkaline solutions, either in an openvessel or under pressure, (endangering life by risk of explosion;)neither do we claim the use of chloride of lime or sulphuric acid; but

What we claim as our invention, and desire to secure by Letters Patent,is-

The method herein specified of treating straw or similar vegetable fiberfor making white paper by the successive operations of boiling, washing,and separating or beating, and then applying the chemicals used forbleaching to the pulp, substantially as set forth.

In witness whereof we have hereunto set our signatures this 13th day ofJanuary, 1860.

ROBT. T. SMART. J. WV. SMART. A. J. SMART.

Witnesses LEMUEL W. SERRELL, WALTER RALIGH, THos. GEO. HAROLD.

